CN110866352A

CN110866352A - Processing method for rod unit contact calculation

Info

Publication number: CN110866352A
Application number: CN201911023239.XA
Authority: CN
Inventors: 赵少杰; 高洁; 杨华伦
Original assignee: AVIC XAC Commercial Aircraft Co Ltd
Current assignee: AVIC XAC Commercial Aircraft Co Ltd
Priority date: 2019-10-25
Filing date: 2019-10-25
Publication date: 2020-03-06
Anticipated expiration: 2039-10-25
Also published as: CN110866352B

Abstract

A processing method for rod unit contact calculation is characterized in that rod units, solid units and finite element models of corresponding boundary conditions are known, regions where the rod units and the solid units are in contact are determined in the known finite element models, shell units are built in the determined processing regions along the axial direction of each rod unit, the shell units are loaded into the known finite element models to form finite element models, the finite element models are submitted to calculation, and calculation results of the finite element models are output.

Description

Processing method for rod unit contact calculation

Technical Field

The invention belongs to the technical field of intensity calculation, and relates to a contact processing method for a rod unit and other types of entity units.

Background

The finite element method is a numerical analysis method which disperses a continuous solution domain into a finite number of units and approximates a real physical system by using an approximate solution of the finite units under a given constraint condition. The finite element is a minimum solution domain which has geometrical and physical properties after the solution domain is dispersed. The rod unit is a unit in the form of a line segment and only has a limited unit with tension and compression rigidity; the shell unit is a unit in the form of a dough sheet and has limited units of in-plane tension and compression, shear stiffness and out-of-plane bending stiffness; the solid elements are transformed into solid block-shaped elements with limited unit of tension-compression shear stiffness. Most of the current finite element software cannot deal with the problem of rod element contact with other elements. However, there are increasing engineering concerns such as net blocking, belt loading, etc. which must be considered in the design.

The main methods for solving the problem are mainly two types: one is experimental research, the method has huge workload and very high cost; another method is contact numerical calculation, but it is difficult to simulate soft structures such as ropes, and usually shells or membrane units are used. The calculation result is often too large locally and inaccurate. The rod unit can avoid the disadvantages of the shell or membrane unit, but the contact condition cannot be set in most numerical calculation software.

Disclosure of Invention

The purpose of the invention is: a processing method for rod unit contact calculation is provided, and contact setting of a rod unit and other units is realized.

A processing method for rod element contact calculation is disclosed, wherein a finite element model of a known rod element and a known solid element is characterized by comprising the following contents: 1) determining a contact area of the rod unit and the solid unit in the finite element model, wherein the contact area is a processing area; 2) establishing a shell unit along the axial direction of each rod unit in the determined processing area, wherein the shell unit and the corresponding rod unit share a node; 3) setting the thickness of the shell unit and endowing the shell unit with the material properties of the corresponding rod unit; 4) and establishing contact attributes of the shell unit and the entity unit and submitting calculation.

The invention has the advantages that: 1) the principle is simple, the implementation is convenient, and the method can be realized on all commercial software. 2) The rod unit and other types of units can be calculated in a contact mode, and the universal calculation method has the characteristics of universal applicability.

The present application is described in further detail below with reference to the accompanying drawings of embodiments.

Drawings

FIG. 1 is a diagram of a known finite element model.

FIG. 2 is a diagram of a first round finite element model.

FIG. 3 is a cloud of calculated stresses for a final calculated finite element model.

The numbering in the figures illustrates: 1 boundary condition, 2 rod elements, 3 solid elements, 4 shell elements.

Detailed Description

In order to make the real-time objects, technical solutions and advantages of the present invention clearer, the following gives examples to describe in detail the technical details of the implementation of the present invention. In the drawings, the line unit is a rod unit with an area of 80 mm; the solid block hexahedron unit is a solid unit. The described example is an example in which the rod unit is in contact with the body unit in the present invention, and not an example in which all the unit types are in contact, and contact calculation of the rod unit with the rod unit, the rod unit with the case unit, and the like with other unit types is easily achieved according to the present example. The examples described below with reference to the drawings are intended to illustrate the invention and are not to be construed as limiting the invention.

The following describes an example of the contact of the rod unit and the body unit according to the present invention with reference to the drawings.

Step 1: in the known finite element model, including boundary conditions 1 calculated by the finite element model, see fig. 1, it is determined that all rod elements 2 are likely to come into contact with the solid element 3, and all rod elements 2 are determined as the treatment area;

step 2: shell units 4 with the width of 1mm are respectively built on two sides of each rod unit 2 along the axial direction of the rod unit, and the shell units 4 and the corresponding rod units 2 share a node;

and step 3: loading the shell element 4 established in step 2) into a known finite element model to form a first round of finite element model, see fig. 2;

and 4, step 4: setting the thickness of the shell unit 4 to be 0.01mm for the first round of finite element model, endowing the shell unit 4 with the material properties corresponding to the rod unit 2, and forming a second round of finite element model, wherein the elastic modulus is 5000MPa and the Poisson ratio is 0.3;

and 5: establishing a contact condition between the shell unit 4 and the entity unit 3 for the second round of finite element model, wherein the shell unit 4 is a driven surface, and the entity unit 3 is an active surface, so as to form a final calculated finite element model;

step 6: submitting the final finite element model to calculation, and outputting the calculation result of the finite element model, including the stress value of each rod element 2, as shown in fig. 3;

and 7: the maximum stress value calculated by checking all the rod units is 2.49 and the minimum stress value is 2.42, the difference between the maximum value and the minimum value of all the rod units is 0.07MPa, is 0.3 percent of the minimum value of the rod units and is less than 5 percent of the minimum value of the rod units, and the calculation is finished.

Claims

1. A processing method for rod element contact calculation, wherein a finite element model of a rod element, a solid element and corresponding boundary conditions is known, and the method is characterized by comprising the following steps: 1) determining the contact area of the rod unit and the solid unit in the known finite element model, wherein the contact area is a processing area; 2) establishing a shell unit along the axial direction of each rod unit in the determined processing area, wherein the shell unit and the corresponding rod unit share a node; 3) loading the shell unit obtained in the step 2) into a known finite element model to form a first round of finite element model; 4) setting the thickness of the shell unit on the basis of the first round of finite element models, and giving the shell unit the material properties of the corresponding rod unit to form a second round of finite element models; 5) establishing a contact condition between the shell unit and the entity unit on the basis of the second round of finite element model to form a third round of finite element model; 6) submitting the third round of finite element model to calculation, and outputting the calculation result of the finite element model, wherein the calculation result comprises the stress value of each rod unit; 7) comparing whether the difference of the stress values among all the rod units is within a preset threshold range, and if so, finishing the calculation; otherwise, reducing the thickness of the shell unit in the step 4), and reforming a second round finite element model; and repeating the step 5) and the step 6) until the difference of the stress values among all the rod units is within the preset threshold value range.

2. The method for processing rod unit contact calculation according to claim 1, wherein a shell unit is symmetrically built on each of two axial sides of the rod unit.

3. A rod element contact calculation processing method according to claim 1 or 2, wherein the shell element is parallel to the contact surface of the rod element and the solid element as much as possible.

4. A method of processing rod element contact calculations according to claim 3, wherein the width of the shell element is no more than one tenth of the length of the rod element.

5. The method of processing rod element contact calculations according to claim 1, wherein the shell element initial thickness is no more than 0.01 mm.

6. The method of claim 1, wherein the threshold range of the difference between the maximum stress value and the minimum stress value of the rod unit is no greater than 5% of the minimum stress value of the rod unit.